D.L. Huffaker

Publications (66)154 Total impact

• Article: Site-controlled formation of InGaAs quantum nanostructures — Tailoring the dimensionality and the quantum confinement

  B. Liang, P. S. Wong, T. Tran, V. G. Dorogan, Yu. I. Mazur, M. E. Ware, G. J. Salamo, C. K. Shih, D. L. Huffaker
  Nano Research 04/2013; 6(4):235. · 6.97 Impact Factor
• Article: Strong passivation effects on the properties of an InAs surface quantum dot hybrid structure.

  A Lin, B L Liang, V G Dorogan, Yu I Mazur, G G Tarasov, G J Salamo, D L Huffaker
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  ABSTRACT: We report on an InAs quantum dot (QD) hybrid structure with a top surface QD layer coupled to two buried QD layers that is highly sensitive to surface passivation. After 180 min of passivation, the photoluminescence (PL) peak of the surface QDs shifts from 1545 to 1275 nm while its intensity decreases by one order of magnitude. Time-resolved PL reveals a significant decrease of carrier tunneling between the QD layers because of the surface state modification by chemical treatment. A simple model with rate equations is used to explain the observed optical performance. Our results show that the optical performance of this hybrid structure is very sensitive to the surface environment, making it a potential candidate for sensing applications.
  Nanotechnology 01/2013; 24(7):075701. · 3.98 Impact Factor
• Article: Short-Wave Infrared GaInAsSb Photodiodes Grown on GaAs Substrate by Interfacial Misfit Array Technique

  K.C. Nunna, Siew Li Tan, C.J. Reyner, A.R.J. Marshall, Baolai Liang, A. Jallipalli, J.P.R. David, D.L. Huffaker
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  ABSTRACT: We report GaInAsSb-based p - i - n photodiodes operating in the 2-2.4- #x03BC;m wavelength range grown on GaAs (100) substrates using the interfacial misfit (IMF) array technique. A zero-bias dynamic-resistance-area product of 260 #x03A9;cm² and a room temperature peak responsivity of 0.8 A/W (at 2 #x03BC;m) with an estimated maximum detectivity (D*) of 3.8 #x00D7;10¹⁰ cm Hz^1/2 W^-1 is obtained in the photodiodes at -0.2 V. These preliminary results of the IMF-based GaInAsSb detectors are comparable to similar detectors grown on native GaSb substrates demonstrating the potential of the IMF array growth mode to realize high-quality Sb-based infrared detectors on GaAs substrates.
  IEEE Photonics Technology Letters 02/2012; 24(3):218-220. · 2.19 Impact Factor
• Article: Coexistence of type-I and type-II band alignments in antimony-incorporated InAsSb quantum dot nanostructures

  Yu. I. Mazur, V. G. Dorogan, G. J. Salamo, G. G. Tarasov, B. L. Liang, C. J. Reyner, K. Nunna, D. L. Huffaker
  Applied Physics Letters 01/2012; 100:033102. · 3.84 Impact Factor
• Article: Surface plasmon-enhanced nanopillar photodetectors.

  Pradeep Senanayake, Chung-Hong Hung, Joshua Shapiro, Andrew Lin, Baolai Liang, Benjamin S Williams, D L Huffaker
  [show abstract] [hide abstract]
  ABSTRACT: We demonstrate nanopillar-(NP) based plasmon-enhanced photodetectors (NP-PEPDs) operating in the near-infrared spectral regime. A novel fabrication technique produces subwavelength elongated nanoholes in a metal surface self-aligned to patterned NP arrays that acts as a 2D plasmonic crystal. Surface plasmon Polariton Bloch waves (SPP-BWs) are excited by the metal nanohole array resulting in electric field intensity "hot spots" in the NP. The NP periodicity determines the peak responsivity wavelength while the nanohole asymmetry produces polarization-dependent coupling of the SPP-BW modes. Resulting photodetectors have 0.28 A/W responsivity peaked at 1100 nm at a reverse bias of -5 V. Designs for further increasing the optical coupling efficiency into the nanopillar are explored. This technology has potential applications for plasmonically enhanced focal plane arrays and plasmonic photovoltaics.
  Nano Letters 11/2011; 11(12):5279-83. · 13.20 Impact Factor
• Source

  Available from: T. J. Ochalski

  Article: Lateral interdot carrier transfer in an InAs quantum dot cluster grown on a pyramidal GaAs surface.

  B L Liang, P S Wong, N Pavarelli, J Tatebayashi, T J Ochalski, G Huyet, D L Huffaker
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  ABSTRACT: InAs quantum dot clusters (QDCs), which consist of three closely spaced QDs, are formed on nano-facets of GaAs pyramidal structures by selective-area growth using metal-organic chemical vapor deposition. Photoluminescence (PL) and time-resolved PL (TRPL) experiments, measured in the PL linewidth, peak energy and QD emission dynamics indicate lateral carrier transfer within QDCs with an interdot carrier tunneling time of 910 ps under low excitation conditions. This study demonstrates the controlled formation of laterally coupled QDCs, providing a new approach to fabricate patterned QD molecules for optical computing applications.
  Nanotechnology 02/2011; 22(5):055706. · 3.98 Impact Factor
• Article: InGaAs heterostructure formation in catalyst-free GaAs nanopillars by selective-area metal-organic vapor phase epitaxy

  J. N. Shapiro, A. Lin, P. S. Wong, A. C. Scofield, C. Tu, P. N. Senanayake, G. Mariani, B. L. Liang, D. L. Huffaker
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  ABSTRACT: We investigate axial GaAs/InGaAs/GaAs heterostructures embedded in GaAs nanopillars via catalyst-free selective-area metal-organic chemical vapor deposition. Structural characterization by transmission electron microscopy with energy dispersive x-ray spectroscopy (EDS) indicates formation of axial In _x Ga _{1- x} As ( x ∼0.20) inserts with thicknesses from 36 to 220 nm with ±10% variation and graded Ga:In transitions controlled by In segregation. Using the heterointerfaces as markers, the vertical growth rate is determined to increase linearly during growth. Photoluminescence from 77 to 290 K and EDS suggest the presence of strain in the shortest inserts. This capability to control the formation of axial nanopillar heterostructures is crucial for optimized device integration.
  Applied Physics Letters 01/2011; · 3.84 Impact Factor
• Source

  Available from: 144.206.159.178

  Article: 1.52 μm photoluminescence emissions from InAs quantum dots grown on nanopatterned GaAs buffers

  P. S. Wong, B. L. Liang, A. Lin, J. Tatebayashi, D. L. Huffaker
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  ABSTRACT: InAs patterned quantum dots (PQDs) are preferentially formed on faceted GaAs pyramidal buffers using selective-area epitaxy (SAE) by metalorganic chemical vapor deposition. Photoluminescence (PL) wavelength is adjustable through a single parameter, the growth time, and strong room-temperature PL emissions from 1.3 μm to over 1.5 μm are demonstrated, with linear polarization from PQD’s asymmetric geometries. The long wavelength emission is attributed to the large PQD size and the reduced strain within PQDs enabled by SAE. It is thus a viable technique to independently control PL wavelength while maintaining the QD density, and to address single QDs for device applications.
  Applied Physics Letters 10/2010; 97(14):143111-143111-3. · 3.84 Impact Factor
• Source

  Available from: Vitaliy G Dorogan

  Article: Band alignment tailoring of InAs1-xSbx/GaAs quantum dots: control of type I to type II transition.

  J He, C J Reyner, B L Liang, K Nunna, D L Huffaker, N Pavarelli, K Gradkowski, T J Ochalski, G Huyet, V G Dorogan, Yu I Mazur, G J Salamo
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  ABSTRACT: We report the growth of InAs(1-x)Sb(x) self-assembled quantum dots (QDs) on GaAs (100) by molecular beam epitaxy. The optical properties of the QDs are investigated by photoluminescence (PL) and time-resolved photoluminescence (TRPL). A type I to type II band alignment transition is demonstrated by both power-dependent PL and TRPL in InAs(1-x)Sb(x) QD samples with increased Sb beam flux. Results are compared to an eight-band strain-dependent k x p model incorporating detailed QD structure and alloy composition. The calculations show that the conduction band offset of InAs(1-x)Sb(x)/GaAs can be continuously tuned from 0 to 500 meV and a flat conduction band alignment exists when 60% Sb is incorporated into the QDs. Our study offers the possibility of tailoring the band structure of GaAs based InAsSb QDs and opens up new means for device applications.
  Nano Letters 08/2010; 10(8):3052-6. · 13.20 Impact Factor
• Source

  Available from: 144.206.159.178

  Article: Visible light emission from self-catalyzed GaInP/GaP core-shell double heterostructure nanowires on silicon

  J. Tatebayashi, A. Lin, P. S. Wong, R. F. Hick, D. L. Huffaker
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  ABSTRACT: The authors report on the formation, structural analyses, and optical properties of GaInP/GaP self-catalyzed core-shell double heterostructure nanowires (NWs) grown on Si(111) substrates. The NW growth is initiated with the formation of Ga droplets as catalysts, followed by the growth of GaP core and GaInP double heterostructure shells. Structural analyses elucidate the existence of interfaces among GaP core and GaInP double heterostructure shells. Light emissions at 640 and 800 nm are observed at 77 K from GaInP core-shell double heterostructure NWs and surface states of GaInP layers, respectively. The signal from the surface state can be mitigated via surface passivation with ammonium sulfide solution. These results will enable the realization of novel NW-based light-emitting diodes or nanolasers grown on Si substrates utilizing mature Si technologies.
  Journal of Applied Physics 08/2010; 108(3):034315-034315-5. · 2.17 Impact Factor
• Article: Band Alignment Tailoring of InAs1−xSbx/GaAs Quantum Dots: Control of Type I to Type II Transition

  J. He, C. J. Reyner, B. L. Liang, K. Nunna, D. L. Huffaker
  [show abstract] [hide abstract]
  ABSTRACT: We report the growth of InAs1−xSbx self-assembled quantum dots (QDs) on GaAs (100) by molecular beam epitaxy. The optical properties of the QDs are investigated by photoluminescence (PL) and time-resolved photoluminescence (TRPL). A type I to type II band alignment transition is demonstrated by both power-dependent PL and TRPL in InAs1−xSbx QD samples with increased Sb beam flux. Results are compared to an eight-band strain-dependent k·p model incorporating detailed QD structure and alloy composition. The calculations show that the conduction band offset of InAs1−xSbx/GaAs can be continuously tuned from 0 to 500 meV and a flat conduction band alignment exists when 60% Sb is incorporated into the QDs. Our study offers the possibility of tailoring the band structure of GaAs based InAsSb QDs and opens up new means for device applications.Keywords: Quantum dot; band alignment; optical properties
  07/2010;
• Source

  Available from: 144.206.159.178

  Article: Optical characteristics of GaInP/GaP double-heterostructure core-shell nanowires embedded in polydimethylsiloxane membranes

  J. Tatebayashi, G. Mariani, A. Lin, R. F. Hicks, D. L. Huffaker
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  ABSTRACT: The authors report on the optical properties of GaInP/GaP double-heterostructure (DH) core-shell nanowires (NWs) embedded in polydimethylsiloxane (PDMS) membranes. Self-catalyzed NW structures are grown on Si (111) substrates by initiating with the formation of Ga droplets as a catalyst which is followed by the growth of GaP core and GaInP DH shells. Optical characteristics of GaInP/GaP DH core-shell NWs transferred from Si substrates into PDMS membranes show enhanced 77 K light emission at 630 nm. The signal at 775 nm from the surface states of NWs can be mitigated by embedding the NWs in a PDMS membrane that acts as a surface state passivant.
  Applied Physics Letters 06/2010; 96(25):253101-253101-3. · 3.84 Impact Factor
• Article: Electronic characteristics of the interfacial states embedded in “buffer-free” GaSb/GaAs (001) heterojunctions

  A. Jallipalli, K. Nunna, M. N. Kutty, G. Balakrishnan, L. R. Dawson, D. L. Huffaker
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  ABSTRACT: We report a comprehensive study of the electronic properties and compensation of the interfacial states embedded in a majority carrier electron region either on one or both sides of the “buffer-free” GaSb/GaAs (001) heterointerface. An abrupt change observed in the forward-bias current (58 mA) for a small variation in the applied bias (0.05 V) is ascribed to the compensation of the interfacial states due to electron tunneling from GaAs into GaSb. As a result, after the first sweep, the compensated interfacial states exhibit low turn-on voltage (0.35 V) and low reverse-bias currents (30 μA at −5 V). Similar compensation is also obtained via δ-doping or annealing the diodes. The diodes analyzed in this study are useful as the heterointerface is embedded in the majority electron region resembles with that of the n-cladding region of p-i-n structures such as lasers, detectors, and solar cells.
  Applied Physics Letters 11/2009; 95(20):202107-202107-3. · 3.84 Impact Factor
• Article: Monolithically Integrated III-Sb-Based Laser Diodes Grown on Miscut Si Substrates

  J. Tatebayashi, A. Jallipalli, M.N. Kutty, Shenghong Huang, K. Nunna, G. Balakrishnan, L.R. Dawson, D.L. Huffaker
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  ABSTRACT: We report the formation and growth characteristics of an interfacial misfit (IMF) array between AlSb and Si and its application to III-Sb-based quantum-well broad-area edge-emitting laser diodes monolithically grown on an Si (001) substrate. A 13% lattice mismatch between AlSb and Si is accommodated by using the IMF array. A use of 5deg miscut Si substrates enables simultaneous IMF formation and suppression of an antiphase domain, resulting in a drastic suppression of dislocation density over the III-Sb epilayer and realization of electrically injected laser diodes operating at 77 K. The current-voltage characteristics indicate a diode turn-on of 0.7 V, which is consistent with a theoretical built-in potential of the laser diode. This device is characterized by a 9.1-Omega forward resistance and a leakage current density of 0.7 A/cm² at -5 V and 46.9 A/cm² at -15 V.
  IEEE Journal of Selected Topics in Quantum Electronics 07/2009; · 3.78 Impact Factor
• Article: Formation and Optical Characteristics of Type-II Strain-Relieved GaSb/GaAs Quantum Dots by Using an Interfacial Misfit Growth Mode

  J. Tatebayashi, Baolai Liang, D.A. Bussian, H. Htoon, Shenghong Huang, G. Balakrishnan, V. Klimov, L.R. Dawson, D.L. Huffaker
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  ABSTRACT: We report the formation and optical characteristics of GaSb/GaAs type-II quantum dots (QDs) by using an interfacial misfit (IMF) growth mode. A V/III ratio during the growth of GaSb QDs determines the selectivity of IMF and conventional Stranski-Krastanov (SK) growth modes. This transition between SK and optimized IMF QDs is rather abrupt and occurs within a factor-of-2 variations in V/III ratio. The IMF QDs emit at longer wavelength (cong1.1 mum) compared to the SK QD peak emission at cong1.02 mum at low temperature (LT) (4 K) because of their strain-free nature of the IMF growth mode. A blueshift of the photoluminescence (PL) peak is observed with increased excitation densities due to the Coulomb interaction between physically separated electrons and holes characteristics of the type-II band alignment. LT time-resolved PL measurements show a long decay time of cong20-40 ns from the transition between GaSb IMF QDs and GaAs 2-D electron gas, which is characteristic of the type-II band alignment.
  IEEE Transactions on Nanotechnology 04/2009; · 2.29 Impact Factor
• Article: Strain compensation technique in self-assembled InAs/GaAs quantum dots for applications to photonic devices

  J Tatebayashi, N Nuntawong, P S Wong, Y-C Xin, L F Lester, D L Huffaker
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  ABSTRACT: We report the strain compensation (SC) technique for a stacked InAs/GaAs self-assembled quantum dot (QD) structure grown by metalorganic chemical vapour deposition (MOCVD). Several techniques are used to investigate the effect of the SC technique: the high-resolution x-ray diffraction (XRD) technique is used to quantify the reduction in overall strain, atomic force spectroscopy is used to reveal that the SC layer improves the QD uniformity and reduces the defect density and photoluminescence characterization is used to quantify the optical property of stacked InAs QDs. In addition, experimental and mathematical evaluation of reduction in the strain field in the compensated structure is conducted. We identify two types of strain in stacked QD samples, homogeneous and inhomogeneous strain. XRD spectra indicate that vi > 36% reduction in the homogeneous strain can be accomplished. Inhomogeneous strain field is investigated by studying the strain coupling probability as a function of the spacer thickness, indicating that 19% reduction in inhomogeneous strain within SC structures has been evaluated. Next, device application of SC techniques including lasers and modulators is reported. Room temperature ground-state lasing from 6-stack InAs QDs with GaP SC is realized at a lasing wavelength of 1265 nm with a threshold current density of 108 A cm−2. The electro-optic (EO) properties of 1.3 µm self-assembled InAs/GaAs QDs are investigated. The linear and quadratic EO coefficients are 2.4 × 10−11 m V−1 and 3.2 × 10−18 m2 V−2, respectively, which are significantly larger than those of GaAs bulk materials. Also, the linear EO coefficient is almost comparable to that of lithium niobate.
  Journal of Physics D Applied Physics 03/2009; 42(7):073002. · 2.54 Impact Factor
• Article: Fabrication and characteristics of broad-area light-emitting diode based on nanopatterned quantum dots.

  P S Wong, B L Liang, J Tatebayashi, L Xue, N Nuntawong, M N Kutty, S R J Brueck, D L Huffaker
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  ABSTRACT: The device fabrication and integration of nanopatterned quantum dots (PQDs) are realized through the demonstration of a broad-area light-emitting diode with PQD active region. The device involves two growth processes, first to form PQDs by selective-area epitaxy on an SiO(2) mask and then to complete the device structure after mask removal. Linear current-voltage characteristics are observed with sharp turn-on, low leakage current and low forward resistance. Electroluminescence spectra show PQD intraband structure and low quenching of emission from 77 K to room temperature. Light-current measurements demonstrate external quantum efficiency per PQD comparable to self-assembled QDs, thus providing a possible route toward individually addressable single QD devices.
  Nanotechnology 02/2009; 20(3):035302. · 3.98 Impact Factor
• Article: Device Characteristics of GaInSb/AlGaSb Quantum Well Lasers Monolithically Grown on GaAs Substrates by Using an Interfacial Misfit Array

  J. Tatebayashi, A. Jallipalli, M.N. Kutty, S.H. Huang, T.J. Rotter, G. Balakrishnan, L.R. Dawson, D.L. Huffaker
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  ABSTRACT: We report the device characteristics of GaInSb/AlGaSb quantum well (QW) lasers monolithically grown on GaAs substrates by using an interfacial misfit (IMF) array. The IMF array localized at the GaSb/GaAs interface can accommodate the 7.8% lattice mismatch between GaAs substrates and GaSb buffer layers, resulting in the formation of a GaSb buffer with a very low defect density on GaAs substrates. Top-top and top-bottom metal contact methods are applied to the Ga0.9In0.1Sb/GaSb QW edge-emitting lasers monolithically grown on GaAs substrates for characterizing current–voltage (I–V) and output power–current (L–I) curves. The potential drop at the IMF array of ~0.7V is elucidated by comparing I–V characteristics with these two contact methods. L–I characteristics and electroluminescence spectra shows room-temperature lasing at 1.83μm from a 1.25-mm-long top-top contact device containing six-layer Ga0.9In0.1Sb QWs with a threshold current density (J th) of 860kA/cm2. This IMF technique will enable a wide range of lasing wavelengths from near- to mid-wavelength infrared regimes on a GaAs platform.
  Journal of Electronic Materials 11/2008; 37(12):1758-1763. · 1.47 Impact Factor
• Source

  Available from: Noppadon Nuntawong

  Article: Improved photoluminescence efficiency of patterned quantum dots incorporating a dots-in-the-well structure.

  P S Wong, B L Liang, V G Dorogan, A R Albrecht, J Tatebayashi, X He, N Nuntawong, Yu I Mazur, G J Salamo, S R J Brueck, D L Huffaker
  [show abstract] [hide abstract]
  ABSTRACT: InAs quantum dots embedded in InGaAs quantum well (DWELL: dots-in-the-well) structures grown on nanopatterned GaAs pyramids and planar GaAs(001) surface are comparatively investigated. Photoluminescence (PL) measurements demonstrate that the DWELL structure grown on the GaAs pyramids exhibits a broad quantum well PL band (full width at half-maximum ∼ 90 meV) and a higher quantum dot emission efficiency than the DWELL structure grown on the planar GaAs(001) substrate. These properties are attributed to the InGaAs quantum well with distributed thickness profile on the faceted GaAs pyramids, which introduces a tapered energy band structure and enhances carrier capture into the quantum dots.
  Nanotechnology 10/2008; 19(43):435710. · 3.98 Impact Factor
• Source

  Available from: chtm.unm.edu

  Article: Simultaneous interfacial misfit array formation and antiphase domain suppression on miscut silicon substrate

  S. H. Huang, G. Balakrishnan, A. Khoshakhlagh, L. R. Dawson, D. L. Huffaker
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  ABSTRACT: The authors describe simultaneous interfacial misfit (IMF) array formation along with antiphase domain (APD) suppression in highly mismatched (Δa0/a0 = 13%) AlSb grown on a 5° miscut Si (001) substrate. Strain energy from the AlSb/Si heterojunction is accommodated by a self-assembled two-dimensional array of pure 90° dislocations confined to the interface. The 13% lattice mismatch establishes the AlSb/Si IMF period of ∼ 3.46 nm. This IMF spacing is well matched to the step length of the 5° miscut Si (001) substrate. Furthermore, the miscut substrate geometry suppresses APD formation due to the double step height. The resulting bulk material has both very low defect density ( ∼ 7×105/cm2) and very low APD density ( ∼ 103/cm2) confirmed by transmission electron microscope images. This material is expected to be desirable for electronic III-V devices on Si substrates.
  Applied Physics Letters 08/2008; 93(7):071102-071102-3. · 3.84 Impact Factor